## Physics MCQs Topic Optics

1.light of wavelength lambda is incident normally on a diffraction grating for which the slit spacing is equal to 3 lambda.what is the sine of angle between the second order maximum and the normal?
a.1 / 6
b.1 / 3
c.2 / 3
d.3 / 2

2. Light of wavelength lambda is incident normally on a diffraction grating for which the slit spacing is equal to         3 lambda.what is the sine of angle between the second order maximum and the normal?
a.1 / 6
b.1 / 3

c.2 / 3
d.3 / 2

3.a diffraction grating has 500 lines per mm its slit spacing will be
a.5*103  mm
b.5*10-3 mm
c.2*103 mm

d.2*10-3 mm

4.for which of the following colors will the fring width be minimum in the double slit experiment?
a.violet
b.red
c.green
d.yellow

5. in single slit experiment, increasing the width of slit results in
a. widening the diffraction pattern
b. narrowing the diffraction pattern
c. no change in the diffraction pattern
d. reversing the diffraction pattern

6.increasing the number of lines per centimeter (the ruling) on diffraction grating
a.allows one to use longer wavelengths of light
b.allows one to use shorter wavelengths of light
c.increases the spread of the spacing between principal maxima
d.decreases the spread of the spacing between principal maxima

7. the spreading of light from its original line of travel is called
a. reflaction
b. refraction
c. diffraction
d. dispersion

8. in double slit interference pattern , using different wavelength of light to produce the fringes , the fringes are closer together when the slit is illuminated with
a. blue light
b.green light
c. yellow light
d. orange light
e. 677nm

9.in double-slit interference pattern, destructive interfernce occurs when the path difference between two waves is
a.even multiples of lambda by 2
b.odd multiples of lambda by 2
c.the same
d.even multiples of lambda
e.odd multples of lambda

10.in double-slit interference pattern, decreasing the distance, d, between the slits causes  the width of the fringes to
a.increase
b.decrease
c.remain the same
d.increase then decrease
e.decrease then increase

11.in double-slit interference pattern, decreasing the distance, d, between the slits by 1 / 2 results in change in the distance between the fringes by factor of
a.1/4
b.1/2
c.1
d.2
e.4

12.two sources are said to be coherent. this means they
a.are polarized
b.have the same amplitude
c.have different wavelenghts
d.maintain constant phase with respect to each other
e.have different frequencies

13.polarization showed the light wave
a.transverse
b.longitudinal
c.standings
d.sitting

14.why did young place a slit between the light source and the double slits?
a.single source of light is needed
b.light needs to escape the system
c.to filter out other colours of light
d.to make the light wave coherent

15.why are the edges of shadows often fuzzy?
a.interference ocuurs on the object on which the shadow is falling
c.light diffracts around the edges of the object
d.the edges of the original objects are fuzzy

16.why did young place a slit between the light source and the double slits?
a.single source of light is needed
b.light needs to escape the system
c.to filter out other colours of light
d.to make the light wave coherent

17.polarization showed the light wave
a.transverse
b.longitudinal
c.standings
d.sitting

18.the distance between the slits in a double slit setup compared to the distance to the screen from the slit is
b.very small
c.very large
d.no important in the experiment

19.when un-polarized beam of light is incident on a glass slab, the reflected beam is found to be completely plane polarized.what is the angle between the reflected and the transmitted beam?
a.90o
b.1800
c.45o
d.30o

20.the maximum number of possible interference maxima for slit separation equal to twice the wavelength in young's double slit experiment is
a.infinite
b.three
c.five
d.zero

21.the bright and dark bands you see in a photograph of a double slit interference pattern represent
a.the respective positions of the crests and troughs of the light wave
b.an interference pattern that is not present unless it is produced by the camera lens
c.locations of constructive / destructive interference of light from the two sources
d.constructive interference of light from the two sources
e.the presence of bright and dark particles of light